Overcoming Drug Resistance by Targeting Cancer Bioenergetics with an Activatable Prodrug

Lysosome-Mitochondria Cascade Targeting Nanoparticle Drives Robust Pyroptosis for Cancer Immunotherapy

The subcellular distribution of cargoes plays a crucial role in determining cell fate and therapeutic efficacy. However, achieving the precise delivery of therapeutics to specific intracellular targets remains a significant challenge. Here, we present a trimodular and acid/enzyme-gated nanoplatform (TAEN) that undergoes disassembly within acidic endosomes and then is cleaved by lysosomal cathepsin B to facilitate efficient and targeted transport of released cargoes into mitochondria compartments. By utilizing this nanovehicle, we successfully achieve selective sorting of photosensitizer molecules into mitochondria with a colocalization coefficient of up to 0.98, leading to the generation of reactive oxygen species stress specifically within the mitochondria for potent pyroptosis-based cancer therapy. The induction of mitochondrial stress triggers the intrinsic apoptotic pathway as well as caspase-3/gasdermin-E (GSDME) cascade, resulting in an enhanced cancer cell killing efficacy by nearly 2 orders of magnitude as compared to lysosomal stress. Furthermore, due to its superior capability to stimulate both innate and adaptive immune responses, our mitochondria-sorted nanophotosensitizer exhibits robust antitumor immune efficacy in multiple tumor-bearing mice models. This study not only provides insights into engineering nanomedicines for subcellular targeted delivery but also offers a valuable toolkit for advanced research in the field of nanobiology at subcellular resolution.

Mitochondrial signaling pathways and their role in cancer drug resistance

Mitochondria, traditionally known as cellular powerhouses, now emerge as critical signaling centers influencing cancer progression and drug resistance. The review highlights the role that apoptotic signaling, DNA mutations, mitochondrial dynamics and metabolism play in the development of resistance mechanisms and the advancement of cancer. Targeted approaches are discussed, with an emphasis on managing mitophagy, fusion, and fission of the mitochondria to make resistant cancer cells more susceptible to traditional treatments. Additionally, metabolic reprogramming can be used to effectively target metabolic enzymes such GLUT1, HKII, PDK, and PKM2 in order to avoid resistance mechanisms. Although there are potential possibilities for therapy, the complex structure of mitochondria and their subtle role in tumor development hamper clinical translation. Novel targeted medicines are put forth, providing fresh insights on combating drug resistance in cancer. The study also emphasizes the significance of glutamine metabolism, mitochondrial respiratory complexes, and apoptotic pathways as potential targets to improve treatment effectiveness against drug-resistant cancers. Combining complementary and nanoparticle-based techniques to target mitochondria has demonstrated encouraging results in the treatment of cancer, opening doors to reduce resistance and enable individualized treatment plans catered to the unique characteristics of each patient. Suggesting innovative approaches such as drug repositioning and mitochondrial drug delivery to enhance the efficacy of mitochondria-targeting therapies, presenting a pathway for advancements in cancer treatment. This thorough investigation is a major step forward in the treatment of cancer and has the potential to influence clinical practice and enhance patient outcomes.

A Pyroptosis-Inducing Arsenic(III) Nanomicelle Platform for Synergistic Cancer Immunotherapy

Immunogenic cell death (ICD) could activate anti-tumor immune responses, which is highly attractive for improving cancer treatment effectiveness. Here, this work reports a multifunctional arsenic(III) allosteric inhibitor Mech02, which induces excessive accumulation of 1O2 through sensitized biocatalytic reactions, leading to cell pyroptosis and amplified ICD effect. After Mech02 is converted to Mech03, it could actualize stronger binding effects on the allosteric pocket of pyruvate kinase M2, further interfering with the anaerobic glycolysis pathway of tumors. The enhanced DNA damage triggered by Mech02 and the pyroptosis of cancer stem cells provide assurance for complete tumor clearance. In vivo experiments prove nanomicelle Mech02-HA NPs is able to activate immune memory effects and raise the persistence of anti-tumor immunity. In summary, this study for the first time to introduce the arsenic(III) pharmacophore as an enhanced ICD effect initiator into nitrogen mustard, providing insights for the development of efficient multimodal tumor therapy agents.

Strategies for the development of stimuli-responsive small molecule prodrugs for cancer treatment

Approved anticancer drugs typically face challenges due to their narrow therapeutic window, primarily because of high systemic toxicity and limited selectivity for tumors. Prodrugs are initially inactive drug molecules designed to undergo specific chemical modifications. These modifications render the drugs inactive until they encounter specific conditions or biomarkers in vivo, at which point they are converted into active drug molecules. This thoughtful design significantly improves the efficacy of anticancer drug delivery by enhancing tumor specificity and minimizing off-target effects. Recent advancements in prodrug design have focused on integrating these strategies with delivery systems like liposomes, micelles, and polymerosomes to further improve targeting and reduce side effects. This review outlines strategies for designing stimuli-responsive small molecule prodrugs focused on cancer treatment, emphasizing their chemical structures and the mechanisms controlling drug release. By providing a comprehensive overview, we aim to highlight the potential of these innovative approaches to revolutionize cancer therapy.

A Hypochlorite-Activated Theranostic Prodrug for Selective Imaging of High Myeloperoxidase Expression Acute Myeloid Leukemia Cells and Drug Release

Acute myeloid leukemia (AML) is a fatal hematologic disease. Diagnosis and proper treatment are important for prognosis. High myeloperoxidase (MPO) expression AML cells are characterized with high levels of hypochlorite (ClO-). In this study, we report a ClO--activated theranostic agent, FNC, for AML therapy. FNC responds to ClO- specifically in high MPO expression AML cells, resulting in bright fluorescence and chlorambucil release. FNC can be used to quickly distinguish high MPO expression AML cells from other cells, including low MPO expression leukemia and activated inflammatory cells. FNC exhibits selective toxicity to highly MPO expression AML cells and can efficiently inhibit tumor growth. Meanwhile, FNC can be used to indicate differentiation through the detection of ClO-.

A Λ-Ir(iii)-phenylquinazolinone complex enhances ferroptosis by selectively inhibiting metallothionein-1

Chirality plays an indispensable role in various biological processes, and interactions between chiral enantiomers and biomolecular targets provide new perspectives in precision drug development. While ferroptosis has received increasing attention as a novel pathway to reverse drug resistance, work on the design of precise ferroptosis-targeting molecules through chiral programming was limited. In this work, we designed and synthesized a pair of chirality-dependent ferroptosis-inducing Ir(iii)-phenylquinazolinone complexes (Δ-IrPPQ and Λ-IrPPQ) by inhibiting ferroptosis suppressor protein-1 (FSP1), while the pair of IrPPQ complexes induced extremely different ferroptosis effects as well as distinct photodynamic therapy (PDT) responses toward pancreatic cancer cells. Interestingly, this chirality-dependent biological mechanism through proteomic analysis and molecular simulation revealed that the specific binding and inhibition of metallothionein-1 (MT1) by Λ-IrPPQ sensitized cancer cells to ferroptosis, inducing a burst of reactive oxygen species, lipid peroxidation, glutathione depletion, and inactivation of FSP1. While in comparison, Δ-IrPPQ induced mild ferroptotic cell death. Through simple chiral resolution, the obtained Λ-IrPPQ achieved precise regulation of ferroptosis in pancreatic cancer cells. This work provides new insights into the design of chiral ferroptosis-inducing metallodrugs for future pancreatic cancer therapy.

Progress and Challenges in Tumor Ferroptosis Treatment Strategies: A Comprehensive Review of Metal Complexes and Nanomedicine

Ferroptosis is a new form of regulated cell death featuring iron-dependent lipid peroxides accumulation to kill tumor cells. A growing body of evidence has shown the potential of ferroptosis-based cancer therapy in eradicating refractory malignancies that are resistant to apoptosis-based conventional therapies. In recent years, studies have reported a number of ferroptosis inducers that can increase the vulnerability of tumor cells to ferroptosis by regulating ferroptosis-related signaling pathways. Encouraged by the rapid development of ferroptosis-driven cancer therapies, interdisciplinary fields that combine ferroptosis, pharmaceutical chemistry, and nanotechnology are focused. First, the prerequisites and metabolic pathways for ferroptosis are briefly introduced. Then, in detail emerging ferroptosis inducers designed to boost ferroptosis-induced tumor therapy, including metal complexes, metal-based nanoparticles, and metal-free nanoparticles are summarized. Subsequently, the application of synergistic strategies that combine ferroptosis with apoptosis and other regulated cell death for cancer therapy, with emphasis on the use of both cuproptosis and ferroptosis to induce redox dysregulation in tumor and intracellular bimetallic copper/iron metabolism disorders during tumor treatment is discussed. Finally, challenges associated with clinical translation and potential future directions for potentiating cancer ferroptosis therapies are highlighted.

Glutathione-triggered prodrugs: Design strategies, potential applications, and perspectives

The burgeoning prodrug strategy offers a promising avenue toward improving the efficacy and specificity of cytotoxic drugs. Elevated intracellular levels of glutathione (GSH) have been regarded as a hallmark of tumor cells and characteristic feature of the tumor microenvironment. Considering the pivotal involvement of elevated GSH in the tumorigenic process, a diverse repertoire of GSH-triggered prodrugs has been developed for cancer therapy, facilitating the attenuation of deleterious side effects associated with conventional chemotherapeutic agents and/or the attainment of more efficacious therapeutic outcomes. These prodrug formulations encompass a spectrum of architectures, spanning from small molecules to polymer-based and organic-inorganic nanomaterial constructs. Although the GSH-triggered prodrugs have been gaining increasing interests, a comprehensive review of the advancements made in the field is still lacking. To fill the existing lacuna, this review undertakes a retrospective analysis of noteworthy research endeavors, based on a categorization of these molecules by their diverse recognition units (i.e., disulfides, diselenides, Michael acceptors, and sulfonamides/sulfonates). This review also focuses on explaining the distinct benefits of employing various chemical architecture strategies in the design of these prodrug agents. Furthermore, we highlight the potential for synergistic functionality by incorporating multiple-targeting conjugates, theranostic entities, and combinational treatment modalities, all of which rely on the GSH-triggering. Overall, an extensive overview of the emerging field is presented in this review, highlighting the obstacles and opportunities that lie ahead. Our overarching goal is to furnish methodological guidance for the development of more efficacious GSH-triggered prodrugs in the future. By assessing the pros and cons of current GSH-triggered prodrugs, we expect that this review will be a handful reference for prodrug design, and would provide a guidance for improving the properties of prodrugs and discovering novel trigger scaffolds for constructing GSH-triggered prodrugs.

Recent Progress of Supramolecular Chemotherapy Based on Host-Guest Interactions

Chemotherapy is widely recognized as an effective approach for treating cancer due to its ability to eliminate cancer cells using chemotherapeutic drugs. However, traditional chemotherapy suffers from various drawbacks, including limited solubility and stability of drugs, severe side effects, low bioavailability, drug resistance, and challenges in tracking treatment efficacy. These limitations greatly hinder its widespread clinical application. In contrast, supramolecular chemotherapy, which relies on host-guest interactions, presents a promising alternative by offering highly efficient and minimally toxic anticancer drug delivery. In this review, an overview of recent advancements in supramolecular chemotherapy based on host-guest interactions is provided. The significant role it plays in guiding cancer therapy is emphasized. Drawing on a wealth of cutting-edge research, herein, a timely and valuable resource for individuals interested in the field of supramolecular chemotherapy or cancer therapy, is presented. Furthermore, this review contributes to the progression of the field of supramolecular chemotherapy toward clinical application.

Enhancing lipid peroxidation via radical chain transfer reaction for MRI guided and effective cancer therapy in mice

Lipid peroxidation (LPO), the process of membrane lipid oxidation, is a potential new form of cell death for cancer treatment. However, the radical chain reaction involved in LPO is comprised of the initiation, propagation (the slowest step), and termination stages, limiting its effectiveness in vivo. To address this limitation, we introduce the radical chain transfer reaction into the LPO process to target the propagation step and overcome the sluggish rate of lipid peroxidation, thereby promoting endogenous lipid peroxidation and enhancing therapeutic outcomes. Firstly, radical chain transfer agent (CTA-1)/Fe nanoparticles (CTA-Fe NPs-1) was synthesized. Notably, CTA-1 convert low activity peroxyl radicals (ROO·) into high activity alkoxyl radicals (RO·), creating the cycle of free radical oxidation and increasing the propagation of lipid peroxidation. Additionally, CTA-1/Fe ions enhance reactive oxygen species (ROS) generation, consume glutathione (GSH), and thereby inactivate GPX-4, promoting the initiation stage and reducing termination of free radical reaction. CTA-Fe NPs-1 induce a higher level of peroxidation of polyunsaturated fatty acids in lipid membranes, leading to highly effective treatment in cancer cells. In addition, CTA-Fe NPs-1 could be enriched in tumors inducing potent tumor inhibition and exhibit activatable T1-MRI contrast of magnetic resonance imaging (MRI). In summary, CTA-Fe NPs-1 can enhance intracellular lipid peroxidation by accelerating initiation, propagation, and inhibiting termination step, promoting the cycle of free radical reaction, resulting in effective anticancer outcomes in tumor-bearing mice.

Theranostic Fluorescent Probes

The ability to gain spatiotemporal information, and in some cases achieve spatiotemporal control, in the context of drug delivery makes theranostic fluorescent probes an attractive and intensely investigated research topic. This interest is reflected in the steep rise in publications on the topic that have appeared over the past decade. Theranostic fluorescent probes, in their various incarnations, generally comprise a fluorophore linked to a masked drug, in which the drug is released as the result of certain stimuli, with both intrinsic and extrinsic stimuli being reported. This release is then signaled by the emergence of a fluorescent signal. Importantly, the use of appropriate fluorophores has enabled not only this emerging fluorescence as a spatiotemporal marker for drug delivery but also has provided modalities useful in photodynamic, photothermal, and sonodynamic therapeutic applications. In this review we highlight recent work on theranostic fluorescent probes with a particular focus on probes that are activated in tumor microenvironments. We also summarize efforts to develop probes for other applications, such as neurodegenerative diseases and antibacterials. This review celebrates the diversity of designs reported to date, from discrete small-molecule systems to nanomaterials. Our aim is to provide insights into the potential clinical impact of this still-emerging research direction.

Two-dimensional multifunctional nanosheets as radiosensitizers for chemodynamic/radio-therapy

The hypoxia tumor microenvironment and low radiation attenuation coefficient of tumor tissue usually limit the efficiency of radiotherapy. In this study, a two-dimensional multifunctional nano-sensitizer, CuNS@Pt, was prepared to function as a radiosensitizer, enhancing radiotherapy through multiple mechanisms. Numerous active sites were provided for the deposition of X-ray radiation energy by the in-situ chemical reduction of Pt to create functional hybrids on Cu-based nanosheets. CuNS@Pt catalyzed high concentration of endogenous hydrogen peroxide to generate oxygen in tumor microenvironment, alleviating the physiological environment of hypoxic tumors. Additionally, CuNS could reduce the content of intrinsic glutathione (GSH) and catalyze hydrogen peroxide to form hydroxyl radicals (·OH). The generated ·OH could damage mitochondria and destroy redox homeostasis due to the functional inclusion of Cu species, thereby achieving chemodynamic therapy and further improving the radiation effect. Both in vivo and in vitro experiments showed that the nano sensitizer effectively improved the therapeutic efficiency of radiotherapy and had good biological safety. All in all, this study provides a pragmatic and doable platform for maximizing the efficacy of RT in cancer. This study also highlights the future research value of two-dimensional nanomaterials.

Chimeric Small Molecules for Detouring Drugs into Mitochondria to Engender Apoptosis in Cancer Cells

Mitochondrion has appeared as one of the important targets for anti-cancer therapy. Subsequently, small molecule anti-cancer drugs are directed to the mitochondria for improved therapeutic efficacy. However, simultaneous imaging and impairing mitochondria by a single probe remained a major challenge. To address this, herein Chimeric Small Molecules (CSMs) encompassing drugs, fluorophore and mitochondria homing moiety were designed and synthesized through a concise strategy. Screening of the CSMs in a panel of cancer cell lines (HeLa, MCF7, A549, and HCT-116) revealed that one of the CSMs comprising Indomethacin V exhibited remarkable cervical cancer cell (HeLa) killing (IC50 =0.97 μM). This lead CSM homed into the mitochondria of HeLa cells within 1 h followed by mitochondrial damage and reactive oxygen species (ROS) generation. This novel Indomethacin V-based CSM-mediated mitochondrial damage induced programmed cell death (apoptosis). We anticipate these CSMs can be used as tools to understand the drug effects in organelle chemical biology in diseased states.

Synchronized activating therapeutic nano-agent: Enhancement and tracing for hypoxia-induced chemotherapy

Prodrug is a potential regime to overcome serious adverse events and off-target effects of chemotherapy agents. Among various prodrug activators, hypoxia stands out owing to the generalizability and prominence in tumor micro-environment. However, existing hypoxia activating prodrugs generally face the limitations of stringent structural requirements, the lack of feedback and the singularity of therapeutic modality, which is imputed to the traditional paradigm that recognition groups must be located at the terminus of prodrugs. Herein, a multifunctional nano-prodrug Mal@Cy-NTR-CB has been designed. In this nano-prodrug, a self-destructive tether is introduced to break the mindset, and achieves the activation by hypoxia of chemotherapy based on Chlorambucil (CB), whose efficacy can be augmented and traced by photodynamic therapy (PDT) and fluorescence from Cyanine dyes (Cy). In addition, Maleimide (Mal) carried by the nano-shells can regulate glutathione (GSH) content, preventing 1O2 scavenging, so as to realize PDT sensitization. Experiments demonstrate that Mal@Cy-NTR-CB specifically responds to hypoxic tumors, and achieve synchronous activation, enhancement and feedback of chemotherapy and PDT, inhibiting the tumor growth effectively. This study broadens the design ideas of activatable prodrugs and provides the possibility of multifunctional nano-prodrugs to improve the generalization and prognosis in precision oncology.

Development of 5-fluorouracil-dichloroacetate mutual prodrugs as anticancer agents

5-Fluorouracil (5-FU) is one of the most widely applied chemotherapeutic agents with a broad spectrum of activity. However, despite this versatile activity, its use poses many limitations. Herein, novel derivatives of 5-FU and dichloroacetic acid have been designed and synthesized as a new type of codrugs, also known as mutual prodrugs, to overcome the drawbacks of 5-FU and enhance its therapeutic efficiency. The stability of the obtained compounds has been tested at various pH values using different analytical techniques, namely HPLC and potentiometry. The antiproliferative activity of the new 5-FU derivatives was assessed in vitro on SK-MEL-28 and WM793 human melanoma cell lines in 2D culture as well as on A549 human lung carcinoma, MDA-MB-231 breast adenocarcinoma, LL24 normal lung tissue, and HMF normal breast tissue as a multicellular 3D spheroid model cultured in standard (static) conditions and with the use of microfluidic systems, which to a great extent resembles the in vivo environment. In all cases, new mutual prodrugs showed a higher cytotoxic activity toward cancer models and lower to normal cell models than the parent 5-FU itself.

Development and characterisation of suitably bioengineered microfibrillar matrix-based 3D prostate cancer model forin vitrodrug testing

Bioengineered 3D models that can mimic patient-specific pathologiesin vitroare valuable tools for developing and validating anticancer therapeutics. In this study, microfibrillar matrices with unique structural and functional properties were fabricated as 3D spherical and disc-shaped scaffolds with highly interconnected pores and the potential of the newly developed scaffolds for developing prostate cancer model has been investigated. The newly developed scaffolds showed improved cell retention upon seeding with cancer cells compared to conventional electrospun scaffolds. They facilitated rapid growth and deposition of cancer-specific extracellular matrix through-the-thickness of the scaffold. Compared to the prostate cancer cells grown in 2D culture, the newly developed prostate cancer model showed increased resistance to the chemodrug Docetaxel regardless of the drug concentration or the treatment frequency. A significant reduction in the cell number was observed within one week after the drug treatment in the 2D culture for both PC3 and patient-derived cells. Interestingly, almost 20%-30% of the cancer cells in the newly developed 3D model survived the drug treatment, and the patient-derived cells were more resistant than the tested cell line PC3. The results from this study indicate the potential of the newly developed prostate cancer model forin vitrodrug testing.

Multifunctional small-molecule theranostic agents for tumor-specific imaging and targeted chemotherapy

Cancer is one of the leading causes of death worldwide. Although great progress has been achieved in cancer diagnosis and treatment, novel therapies are still urgently needed to increase the efficacy and reduce the side effects of conventional therapies. Personalized medicine involves administering patients drugs that are specific to the characteristics of their tumors, and has significantly reduced side effects and increased overall survival rates. Multifunctional theranostic drugs are designed to combine diagnostic and therapeutic functions into a single molecule, which reduces the number of drugs administered to patients and increases patient compliance, and have shown great potential in propelling personalized medicine. This review focuses on multifunctional small-molecule theranostic agents for tumor-specific imaging and targeted chemotherapy, with a particular emphasis placed on highlighting design strategies and application in vitro or in vivo. The challenges and future perspectives of multifunctional small molecules are also discussed.

Lysosome-targeting phenalenones as efficient type I/II photosensitizers for anticancer photodynamic therapy

Development of safe and effective photosensitizers is important for enhancing the efficacy of photodynamic cancer therapy. Phenalenone is a type II photosensitizer with a high singlet oxygen quantum yield; however, its short UV absorption wavelength hinders its application in cancer imaging and in vivo photodynamic therapy. In this study, we report a new redshift phenalenone derivative, 6-amino-5-iodo-1H-phenalen-1-one (SDU Red [SR]), as a lysosome-targeting photosensitizer for triple-negative breast cancer therapy. SDU Red produced singlet oxygen (Type II reactive oxygen species [ROS]) and superoxide anion radicals (Type I ROS) upon light irradiation. It also exhibited good photostability and a remarkable phototherapeutic index (PI > 76) against triple-negative breast cancer MDA-MB-231 cancer cells. Additionally, we designed two amide derivatives, SRE-I and SRE-II, with decreased fluorescence and photosensitizing capabilities based on SDU Red as activatable photosensitizers for photodynamic cancer therapy. SRE-I and SRE-II could be further converted into the active photosensitizer SDU Red via carboxylesterase-catalyzed amide bond cleavage. Moreover, SDU Red and SRE-II induced DNA damage and cell apoptosis in the presence of light. Therefore, SRE-II can act as a promising theranostic agent for triple-negative breast cancer.

Recent trends in emerging strategies for ferroptosis-based cancer therapy

Ferroptosis, an iron-dependent mode of regulated cell death, is induced by lipid peroxidation, whose occurrence and execution are primarily controlled by metabolism of iron, lipids, amino acids and glutathione. In recent years, the fast-growing studies of ferroptosis in cancer have promoted its application in cancer therapy. So, this review focuses on the feasibility and characteristics of initiating ferroptosis for cancer therapy, as well as the main mechanism of ferroptosis. And various emerging strategies of cancer therapy based on ferroptosis are then highlighted to describe their design, mechanism of action, and anticancer applications. In addition ferroptosis in diverse cancer types is summarized, some considerations for the research of various preparations that can cause ferroptosis are introduced, and this emerging field is discussed in terms of its challenges and future development directions.

The design of small-molecule prodrugs and activatable phototherapeutics for cancer therapy

Cancer remains as one of the most significant health problems, with approximately 19 million people diagnosed worldwide each year. Chemotherapy is a routinely used method to treat cancer patients. However, current treatment options lack the appropriate selectivity for cancer cells, are prone to resistance mechanisms, and are plagued with dose-limiting toxicities. As such, researchers have devoted their attention to developing prodrug-based strategies that have the potential to overcome these limitations. This tutorial review highlights recently developed prodrug strategies for cancer therapy. Prodrug examples that provide an integrated diagnostic (fluorescent, photoacoustic, and magnetic resonance imaging) response, which are referred to as theranostics, are also discussed. Owing to the non-invasive nature of light (and X-rays), we have discussed external excitation prodrug strategies as well as examples of activatable photosensitizers that enhance the precision of photodynamic therapy/photothermal therapy. Activatable photosensitizers/photothermal agents can be seen as analogous to prodrugs, with their phototherapeutic properties at a specific wavelength activated in the presence of disease-related biomarkers. We discuss each design strategy and illustrate the importance of targeting biomarkers specific to the tumour microenvironment and biomarkers that are known to be overexpressed within cancer cells. Moreover, we discuss the advantages of each approach and highlight their inherent limitations. We hope in doing so, the reader will appreciate the current challenges and available opportunities in the field and inspire subsequent generations to pursue this crucial area of cancer research.

Topology regulation of nanomedicine for autophagy-augmented ferroptosis and cancer immunotherapy

Iron accumulation and lipid peroxidation form the basis of ferroptosis, potentially circumventing the limitations of apoptosis in cancer treatment. Owing to the lack of potent ferroptosis inducers, the development of efficient ferroptosis-based therapeutic agents and protocols against cancers is highly challenging. Inspired by the topological effect of nanoparticles in modulating cellular function/status, a specific tetrapod ferroptosis-inducer iron-palladium (FePd) nanocrystal was rationally engineered for physically activated autophagy-augmented ferroptosis and enhanced cancer immunotherapy. Specifically, the tetrapod FePd nanocrystal featured strong peroxidase-/glutathione oxidase-mimicking bioactivities, which promoted cancer cell ferroptosis. The special spiky morphology and nanostructure of the FePd nanocrystal simultaneously induced autophagy, which augmented ferroptosis in cancer cells and triggered the release of inflammatory cytokines in macrophages for strengthening anti-PD-L1-antibody mediated immunotherapy, synergistically achieving the maximal antineoplastic effect in three tumor-bearing animal models. This unique physical activation strategy for efficient cancer treatment via precise morphological tuning represents a paradigm for nanomedicine design for efficient tumor treatment.

Cancer Cell Membrane Biomimetic Mesoporous Nanozyme System with Efficient ROS Generation for Antitumor Chemoresistance

Single-atom nanozymes (SAZs) with reaction specificity and optimized catalytic properties have great application prospects in tumor therapy. But the complex tumor microenvironment (low content of H2O2) limits its therapeutic effect. In this study, we developed a bionic mesoporous Fe SAZs/DDP nanosystem (CSD) for enhanced nanocatalytic therapy (NCT)/chemotherapy by simultaneously encapsulating the chemotherapeutic drugs cisplatin (DDP) and Fe SAZs with high peroxidase (POD) activity into the cancer cell membrane. CSD could evade immune recognition and actively targets tumor sites, and DDP upregulates endogenous H2O2 levels by activating nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, thereby enhancing SAZs-mediated hydroxyl radical (·OH) production, which subsequently leads to mitochondrial damage and intolerance to chemotherapy drug. We used the HGC27/DDP cell line for in vitro and in vivo experiments. The results showed that CSD achieved good therapeutic benefits, without any side effects such as inflammatory reaction. This system can induce multiple antitumor effect with H2O2 self-supply, mitochondrial damage, and ATP downregulation and eventually lead to chemosensitization.

An excipient-free "sugar-coated bullet" for the targeted treatment of orthotopic hepatocellular carcinoma

Several components of traditional nanoformulations that result in structural heterogeneity, poor reproducibility, excipient-trigged biotoxicity, and low retention of antitumor drugs in neoplastic foci are important barriers limiting clinical translation. We report an excipient-free nanoformulation prepared by a reactive oxygen species (ROS)-responsive amphiphilic prodrug (Gal-MB-DOX) for the targeted treatment of orthotopic hepatocellular carcinoma (HCC). Gal-MB-DOX can form monocomponent nanoparticles with a galactose-rich surface similar to a "sugar-coated bullet" through self-assembly in aqueous solution. This nanoformulation can be decomposed quickly by ROS and release free hydrophobic drugs that further precipitate into larger particles, potentially promoting the retention of drugs in tumor cells. These sugar-coated bullets selectively target tumor cells through passive and active targeting, resulting in high in vivo therapeutic efficacy in an orthotopic HCC mouse model. This monocomponent nanomedicine system provides a simple but effective strategy for the treatment of tumors.

Nitroreductase-induced bioorthogonal ligation for prodrug activation: A traceless strategy for cancer-specific imaging and therapy

Prodrug development is of great interest in cancer therapy. From bio-friendly standpoints, traceless prodrug activation would be an ideal approach for cancer treatment owning to the avoidance of byproduct which might induce side effects in living system. Here, we report a fully traceless strategy for cancer imaging and therapy via a metal-free bioorthogonal ligation triggered by nitroreductase (NTR) overexpressed in solid tumors. The reduction of nitro substrates to amines by NTR and further condensation of amines with aldehydes can be seamlessly combined to yield imine-based resveratrol (RSV) with water as the only byproduct. In comparison with RSV, this precursor exhibited not only the same level of anticancer efficiency both in vitro and in vivo under hypoxia, but also a high sensitivity to hypoxia and much lower perturbation towards normal cells, which holds a great potential of theranostic prodrug for cancer therapy.

Recapitulated Crosstalk between Cerebral Metastatic Lung Cancer Cells and Brain Perivascular Tumor Microenvironment in a Microfluidic Co-Culture Chip

Non-small cell lung carcinoma (NSCLC), which affects the brain, is fatal and resistant to anti-cancer therapies. Despite innate, distinct characteristics of the brain from other organs, the underlying delicate crosstalk between brain metastatic NSCLC (BM-NSCLC) cells and brain tumor microenvironment (bTME) associated with tumor evolution remains elusive. Here, a novel 3D microfluidic tri-culture platform is proposed for recapitulating positive feedback from BM-NSCLC and astrocytes and brain-specific endothelial cells, two major players in bTME. Advanced imaging and quantitative functional assessment of the 3D tri-culture model enable real-time live imaging of cell viability and separate analyses of genomic/molecular/secretome from each subset. Susceptibility of multiple patient-derived BM-NSCLCs to representative targeted agents is altered and secretion of serpin E1, interleukin-8, and secreted phosphoprotein 1, which are associated with tumor aggressiveness and poor clinical outcome, is increased in tri-culture. Notably, multiple signaling pathways involved in inflammatory responses, nuclear factor kappa-light-chain-enhancer of activated B cells, and cancer metastasis are activated in BM-NSCLC through interaction with two bTME cell types. This novel platform offers a tool to elucidate potential molecular targets and for effective anti-cancer therapy targeting the crosstalk between metastatic cancer cells and adjacent components of bTME.

A Mitochondria-Targeted Phenylbutyric Acid Prodrug Confers Drastically Improved Anticancer Activities

Phenylbutyric acid (PBA) has been reported as a dual inhibitor of pyruvate dehydrogenase kinases (PDKs) and histone deacetylases (HDACs), exhibiting anticancer effects. However, the low membrane permeability and poor cellular uptake limit its access to the target organelle, resulting in weak potencies against the intended targets. Herein, we report the design and identification of a novel 4-CF₃-phenyl triphenylphosphonium-based PBA conjugate (53) with improved in vitro and in vivo anticancer activities. Compound 53 exhibited an IC₅₀ value of 2.22 μM against A375 cells, outperforming the parent drug PBA by about 4000-fold. In the A375 cell-derived xenograft mouse model, 53 reduced the tumor growth by 76% at a dose of 40 mg/kg, while PBA only reduced the tumor growth by 10% at a dose of 80 mg/kg. On the basis of these results, 53 may be considered for further preclinical evaluations for cancer therapy.

DNA-Damage-Response-Targeting Mitochondria-Activated Multifunctional Prodrug Strategy for Self-Defensive Tumor Therapy

We report a novel multifunctional construct, M1, designed explicitly to target the DNA damage response in cancer cells. M1 contains both a floxuridine (FUDR) and protein phosphatase 2A (PP2A) inhibitor combined with a GSH-sensitive linker. Further conjugation of the triphenylphosphonium moiety allows M1 to undergo specific activation in the mitochondria, where mitochondria-mediated apoptosis is observed. Moreover, M1 has enormous effects on genomic DNA ascribed to FUDR's primary function of impeding DNA/RNA synthesis combined with diminishing PP2A-activated DNA repair pathways. Importantly, mechanistic studies highlight the PP2A obtrusion in FUDR/5-fluorouracil (5-FU) therapy and underscore the importance of its inhibition to harbor therapeutic potential. HCT116 cell xenograft-bearing mice that have a low response rate to 5-FU show a prominent effect with M1, emphasizing the importance of DNA damage response targeting strategies using tumor-specific microenvironment-activatable systems.

Alkylgold(III) Complexes Undergo Unprecedented Photo-Induced β-Hydride Elimination and Reduction for Targeted Cancer Therapy

Spatiotemporally controllable activation of prodrugs within tumors is highly desirable for cancer therapy to minimize toxic side effects. Herein we report that stable alkylgold(III) complexes can undergo unprecedented photo-induced β-hydride elimination, releasing alkyl ligands and forming gold(III)-hydride intermediates that could be quickly converted into bioactive [Au^III -S] adducts; meanwhile, the remaining alkylgold(III) complexes can photo-catalytically reduce [Au^III -S] into more bioactive Au^I species. Such photo-reactivities make it possible to functionalize gold complexes on the auxiliary alkyl ligands without attenuating the metal-biomacromolecule interactions. As a result, the gold(III) complexes containing glucose-functionalized alkyl ligands displayed efficient and tumor-selective uptake; notably, after one- or two-photon activation, the complexes exhibited high thioredoxin reductase (TrxR) inhibition, potent cytotoxicity, and strong antiangiogenesis and antitumor activities in vivo.

Redox-Based Strategy for Selectively Inducing Energy Crisis Inside Cancer Cells: An Example of Modifying Dietary Curcumin to Target Mitochondria

Reprograming of energy metabolism is a major hallmark of cancer, but its effective intervention is still a challenging task due to metabolic heterogeneity and plasticity of cancer cells. Herein, we report a general redox-based strategy for meeting the challenge. The strategy was exemplified by a dietary curcumin analogue (MitoCur-1) that was designed to target mitochondria (MitoCur-1). By virtue of its electrophilic and mitochondrial-targeting properties, MitoCur-1 generated reactive oxygen species (ROS) more effectively and selectively in HepG2 cells than in L02 cells via the inhibition of mitochondrial antioxidative thioredoxin reductase 2 (TrxR2). The ROS generation preferentially mediated the energy crisis of HepG2 cells in a dual-inhibition fashion against both mitochondrial and glycolytic metabolisms, which could hit the metabolic plasticity of HepG2 cells. The ROS-dependent energy crisis also allowed its preferential killing of HepG2 cells (IC₅₀ = 1.4 μM) over L02 cells (IC₅₀ = 9.1 μM), via induction of cell-cycle arrest, apoptosis and autophagic death, and its high antitumor efficacy in vivo, in nude mice bearing HepG2 tumors (15 mg/kg). These results highlight that inhibiting mitochondrial TrxR2 to produce ROS by electrophiles is a promising redox-based strategy for the effective intervention of cancer cell energy metabolic reprograming.

High-throughput glycolytic inhibitor discovery targeting glioblastoma by graphite dots-assisted LDI mass spectrometry

Malignant tumors will become vulnerable if their uncontrolled biosynthesis and energy consumption engaged in metabolic reprogramming can be cut off. Here, we report finding a glycolytic inhibitor targeting glioblastoma with graphite dots-assisted laser desorption/ionization mass spectrometry as an integrated drug screening and pharmacokinetic platform (GLMSD). We have performed high-throughput virtual screening to narrow an initial library of 240,000 compounds down to the docking of 40 compounds and identified five previously unknown chemical scaffolds as promising hexokinase-2 inhibitors. The best inhibitor (Compd 27) can regulate the reprogrammed metabolic pathway in U87 glioma cells (median inhibitory concentration ~ 11.3 μM) for tumor suppression. Highly effective therapy against glioblastoma has been demonstrated in both subcutaneous and orthotopic brain tumors by synergizing Compd 27 and temozolomide. Our glycolytic inhibitor discovery can inspire personalized medicine targeting reprogrammed metabolisms of malignant tumors. GLMSD enables large, high-quality data for next-generation artificial intelligence-aided drug development.

Biodegradable Ru-Containing Polycarbonate Micelles for Photoinduced Anticancer Multitherapeutic Agent Delivery and Phototherapy Enhancement

The lack of selectivity between tumor and healthy cells, along with inefficient reactive oxygen species production in solid tumors, are two major impediments to the development of anticancer Ru complexes. The development of photoinduced combination therapy based on biodegradable polymers that can be light activated in the "therapeutic window" would be beneficial for enhancing the therapeutic efficacy of Ru complexes. Herein, a biodegradable Ru-containing polymer (poly(DCARu)) is developed, in which two different therapeutics (the drug and the Ru complex) are rationally integrated and then conjugated to a diblock copolymer (MPEG-b-PMCC) containing hydrophilic poly(ethylene glycol) and cyano-functionalized polycarbonate with good degradability and biocompatibility. The polymer self-assembles into micelles with high drug loading capacity, which can be efficiently internalized into tumor cells. Red light induces the generation of singlet oxygen and the release of anticancer drug-Ru complex conjugates from poly(DCARu) micelles, hence inhibiting tumor cell growth. Furthermore, the phototherapy of polymer micelles demonstrates remarkable inhibition of tumor growth in vivo. Meanwhile, polymer micelles exhibit good biocompatibility with blood and healthy tissues, which opens up opportunities for multitherapeutic agent delivery and enhanced phototherapy.

A camptothecin prodrug induces mitochondria-mediated apoptosis in cancer cells with cascade activations

Mitochondria are crucial regulators of the intrinsic pathway of apoptosis. Herein, we report a photosensitizer-conjugated camptothecin (CPT)-based prodrug for combinative chemo-photodynamic treatment of solid tumors with cascade activations. Upon light irradiation, our prodrug can effectively target the mitochondria of cancer cells, generate singlet oxygen to increase the level of reactive oxygen species (ROS) and trigger ROS-responsive release of CPT, which synergistically induce mitochondrial damage and cause the apoptosis of cancer cells, therefore achieving high therapeutic efficacy for solid tumors and minimized adverse effects to normal tissues. Our prodrug holds great promise as a potent and inspiring means for cancer treatment.

Cell-specific activation of gemcitabine by endogenous H2S stimulation and tracking through simultaneous fluorescence turn-on

The endogenous H₂S-driven theranostic H2S-Gem has been invented. The theranostic prodrug H2S-Gem is selectively activated in cancer cells, releasing active gemcitabine with a simultaneous fluorescence turn-on. H2S-Gem selectively inhibited cancer cell growth compared to the mother chemotherapeutic gemcitabine. Overall, it is a unique protocol for tracking and transporting chemotherapeutic agents to tumor areas without the guidance of tumor-directive ligands.

Novel Approaches of Dysregulating Lysosome Functions in Cancer Cells by Specific Drugs and Its Nanoformulations: A Smart Approach of Modern Therapeutics

The smart strategy of cancer cells to bypass the caspase-dependent apoptotic pathway has led to the discovery of novel anti-cancer approaches including the targeting of lysosomes. Recent discoveries observed that lysosomes perform far beyond just recycling of cellular waste, as these organelles are metabolically very active and mediate several signalling pathways to sense the cellular metabolic status. These organelles also play a significant role in mediating the immune system functions. Thus, direct or indirect lysosome-targeting with different drugs can be considered a novel therapeutic approach in different disease including cancer. Recently, some anticancer lysosomotropic drugs (eg, nortriptyline, siramesine, desipramine) and their nanoformulations have been engineered to specifically accumulate within these organelles. These drugs can enhance lysosome membrane permeabilization (LMP) or disrupt the activity of resident enzymes and protein complexes, like v-ATPase and mTORC1. Other anticancer drugs like doxorubicin, quinacrine, chloroquine and DQ661 have also been used which act through multi-target points. In addition, autophagy inhibitors, ferroptosis inducers and fluorescent probes have also been used as novel theranostic agents. Several lysosome-specific drug nanoformulations like mixed charge and peptide conjugated gold nanoparticles (AuNPs), Au-ZnO hybrid NPs, TPP-PEG-biotin NPs, octadecyl-rhodamine-B and cationic liposomes, etc. have been synthesized by diverse methods. These nanoformulations can target cathepsins, glucose-regulated protein 78, or other lysosome specific proteins in different cancers. The specific targeting of cancer cell lysosomes with drug nanoformulations is quite recent and faces tremendous challenges like toxicity concerns to normal tissues, which may be resolved in future research. The anticancer applications of these nanoformulations have led them up to various stages of clinical trials. Here in this review article, we present the recent updates about the lysosome ultrastructure, its cross-talk with other organelles, and the novel strategies of targeting this organelle in tumor cells as a recent innovative approach of cancer management.

Interfering with Metabolic Profile of Triple-Negative Breast Cancers Using Rationally Designed Metformin Prodrugs

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer, characterized by an aberrant metabolic phenotype with high metastatic capacity, resulting in poor patient prognoses and low survival rates. We designed a series of novel Au^III cyclometalated prodrugs of energy-disrupting Type II antidiabetic drugs namely, metformin and phenformin. Prodrug activation and release of the metformin ligand was achieved by tuning the cyclometalated Au^III fragment. The lead complex 3met was 6000-fold more cytotoxic compared to uncoordinated metformin and significantly reduced tumor burden in mice with aggressive breast cancers with lymphocytic infiltration into tumor tissues. These effects was ascribed to 3met interfering with energy production in TNBCs and inhibiting associated pro-survival responses to induce deadly metabolic catastrophe.

An Amphiphilic PEGylated Peptide Dendron-Gemcitabine Prodrug-Based Nanoagent for Cancer Therapy

An amphiphilic peptide dendrimer conjugated with gemcitabine (GEM), PEGylated dendron-Gly-Phe-Leu-Gly-GEM (PEGylated dendron-GFLG-GEM), is developed as a nano-prodrug for breast cancer therapy. The self-assembled behavior is observed under a transmission electron microscopy and dynamic light scattering. The negatively charged surface and hydrodynamic size of the amphiphilic nanosized prodrug supported that the prodrug can maintain the stability of GEM during circulation and accumulate in the tumor tissue. Drug release assays are conducted to monitor the release of GEM from this nanodrug delivery system in response to the tumor microenvironment, and these assays confirm that GEM released from the nanocarrier is identical to free GEM. The GEM prodrug can prevent proliferation of tumor cells. The therapeutic effect against breast cancer is systematically investigated using an in vivo animal model. Immunohistochemical results are aligned with the significantly enhanced anticancer efficacy of GEM released from the prodrug. This self-assembled amphiphilic drug delivery nanocarrier may broaden the application for GEM and other anticancer agents for breast cancer chemotherapy.

Binary Prodrug of Dichloroacetic Acid and Doxorubicin with Enhanced Anticancer Activity

The inevitable challenge in conventional chemotherapy is to deliver the anticancer drugs to the dense population of tumors cells while minimizing the drug-associated side effects on the normal cells. Cancer cells' preference for glycolysis for energy production is well recognized. Intuitively, taking advantage of such cancer-associated metabolism would be a promising strategy for anticancer drug delivery with minimal side effects. In this investigation, we have designed a binary prodrug PDOX as a sequential drug delivery regimens to realize the combination therapy for cancer. As cancer cells exhibit abrupt metabolism with elevated pyruvate dehydrogenase kinase (PDK) activity, dichloroacetic acid (DCA, a well-known PDK inhibitor) was used in combination with anticancer drug doxorubicin (DOX). The designed molecular prodrug was activated selectively by cancer-associated esterase to deliver DCA and DOX, respectively, and induced synergetic effects. Hence, sequential targeted delivery of molecular prodrug PDOX offers a promising approach to overcome the offside drug toxicity, pharmacokinetics, and biodistribution of individuals and provide an alternative option for cancer treatment.

Novel Engineered Bacterium/Black Phosphorus Quantum Dot Hybrid System for Hypoxic Tumor Targeting and Efficient Photodynamic Therapy

Intratumoral hypoxia significantly constrains the susceptibility of solid tumors to oxygen-dependent photodynamic therapy (PDT), and effort to reverse such hypoxia has achieved limited success to date. Herein, we developed a novel engineered bacterial system capable of targeting hypoxic tumor tissues and efficiently mediating the photodynamic treatment of these tumors. For this system, we genetically engineered Escherichia coli to express catalase, after which we explored an electrostatic adsorption approach to link black phosphorus quantum dots (BPQDs) to the surface of these bacteria, thereby generating an engineered E. coli/BPQDs (EB) system. Following intravenous injection, EB was able to target hypoxic tumor tissues. Subsequent 660 nm laser irradiation drove EB to generate reactive oxygen species (ROS) and destroy the membranes of these bacteria, leading to the release of catalase that subsequently degrades hydrogen peroxide to yield oxygen. Increased oxygen levels alleviate intratumoral hypoxia, thereby enhancing BPQD-mediated photodynamic therapy. This system was able to efficiently kill tumor cells in vivo, exhibiting good therapeutic efficacy. In summary, this study is the first to report the utilization of engineered bacteria to facilitate PDT, and our results highlight new avenues for BPQD-mediated cancer treatment.

Structurally Redesigned Bioorthogonal Reagents for Mitochondria-Specific Prodrug Activation

The development of abiotic chemical reactions that can be performed in an organelle-specific manner can provide new opportunities in drug delivery and cell and chemical biology. However, due to the complexity of the cellular environment, this remains a significant challenge. Here, we introduce structurally redesigned bioorthogonal tetrazine reagents that spontaneously accumulate in mitochondria of live mammalian cells. The attributes leading to their efficient accumulation in the organelle were optimized to include the right combination of lipophilicity and positive delocalized charge. The best performing mitochondriotropic tetrazines enable subcellular chemical release of TCO-caged compounds as we show using fluorogenic substrates and mitochondrial uncoupler niclosamide. Our work demonstrates that a shrewd redesign of common bioorthogonal reagents can lead to their transformation into organelle-specific probes, opening the possibility to activate prodrugs and manipulate biological processes at the subcellular level by using purely chemical tools.